[c#] using if else with eval in aspx page

Is there a way to use an else if on the following eval on the aspx page .

Currently my div is as follows :

  <div class="tooltip" style="display: none">                                                                  
        <div style="text-align: center; font-weight: normal">
                Value = <%# Eval("Percentage") + "%" %>     
        </div>
  </div>

I would like to use the following logic on my div :

If(Percentage < 50)
   display "0 %"
   else 
   display "percentage"

I tried something like this but it doesn't work :

if (<%# Eval("Percentage") %> < 50)
{
    Eval("0");
}
else
{
   <%# Eval("PassPercentage") + "%" %> 
 }

I want to know if such an operation is possible to do on the aspx page. I cannot do it in aspx.cs.

If you are trying to bind is a Model class, you can add a new readonly property to it like:

public string FormattedPercentage
{
    get
    {
        If(this.Percentage < 50)
            return "0 %";
        else 
            return string.Format("{0} %", this.Percentage)        
     }
}

Otherwise you can use Andrei's or kostas ch. suggestions if you cannot modify the class itself

 <%if (System.Configuration.ConfigurationManager.AppSettings["OperationalMode"] != "live") {%>
                        &nbsp;[<%=System.Environment.MachineName%>]
                        <%}%>

<%# (string)Eval("gender") =="M" ? "Male" :"Female"%>

You can try c#

public string ProcessMyDataItem(object myValue)
 {
  if (myValue == null)
   {
   return "0 %"";
  }
   else
  {
     if(Convert.ToInt32(myValue) < 50)
       return "0";
     else
      return myValue.ToString() + "%";
  }

 }

asp

 <div class="tooltip" style="display: none">                                                                  
      <div style="text-align: center; font-weight: normal">
   Value =<%# ProcessMyDataItem(Eval("Percentage")) %> </div>
 </div>